Development Of Electrorheological Polishing Device And Path Planning For Electrorheological Polishing

1. IntroductionThe polishing technology of die and mould is eagerly required because of the complex geometry shape and the continuous increasing of free surface mould. For the application of NC,EDM and CAD/CAM system, the shaping process could implement automatization, but the process of polishing is mainly depended on the abundant experience of the worker. This does not only require workers have excellent technology, but also could never assure the quality stability of the free-surface after polishing. If there is any mistakes during the last phase of polishing, may bring economy expense. Electrorheological polishing applies the polarization of ER fluid in electric field to accomplish polishing. This technology is applicable to small three-dimensional parts.2. Research for the ER polishing theory and development of tooling system(1)Research on the ER polishing theoryAt present, there are four theories such as Fibrillation Model, Double layer deformation Model, Dielectric polarization Model and Conductivity Model.Each of the above theory could explain part of the ER effect, while is difficult to explain certain phenomena, which is an important fact to restrict the development of ER application.(2)Development of tooling systemThe device is developed by Jilin University. To avoid the restriction of the mini space, the tool system of the device is developed. The structure of the developed tool system is shown as fig.1. The two lateral sides of the tool is used as the electrodes in the developed system .When the electric field is imposed on the lateral sides of the tool, the ER effect appears at the end of the tool and the milling particles are tied in the ER fluid. When the polishing tool rotates, the milling particles with the ER fluid in the electric field rotate. Then the milling particles move on the work surface to achieve the polishing progress.3. Reverse modeling for the surface lens and path planning for ER polishing(1)Reverse Modeling for the lensFirst the three coordinate data is gathered by three coordinate measuring machine. Then do the work of grouping fit to these data based on the idea of least squares method and some curves of the surface are got. Then the expression of the generatrix of the lens is confirmed based on the characteristic of lens and the surface expression is got at last.(2)Path planning for ER polishingThe equation of the tool path is based on the expression of lens surface in part 2. Direction-paralleled Machining and Contour-Paralleled Machining are used to be the tool path of the electrorheological polishing for the lens. The tool path are shown in fig.2 (a)and(b),separately. 4. ER Polishing ExperimentsA series of experiments are done using the tool system, such as the ER effect experiment, the experiment that polish the optical glass, polishing the glass using the line path. Last the experiment that polishing the lens using direction-paralleled machining method and contour-paralleled machining is taken out. Fig.3 shows the ER effect experiment, which validates the ER effect could appear at the end of the tool. The experiments that polishing the lens are done on the ER polishing device The 3-dimensional interactive display of one point of the polishing area that using Direction-paralleled Machining is shown as fig.5. 12 contrast points are chosen and the Rt constant before and after polishing is shown as fig.6.Then the lens is polished by Contour-Paralleled Machining path. The polishing parameters are same to table 1 and the 3-dimensional interactive display of one point of polishing area is shown in Fig.7. 20 contrast points are chosen and the Rt constant before and after polishing is shown as Fig. 8.